1. Field of the Invention
The present invention relates a driving circuit (driver) provided in an output stage of an LSI (large-scale integrated circuit) for driving a circuit connected externally to the LSI.
2. Description of the Background Art
A conventional circuit provided in an output stage of an LSI to drive a circuit connected to and provided externally to the LSI, comprises a plurality of stages of CMOS inverters, as described for example in Japanese Patent Kokai Publication No. 2003-133943.
The conventional driving circuit having CMOS inverters has the following problems.    (A1) The delay time at each part of the circuit varies with the ambient temperature, causing irregularities with respect to operation timings. In designing an LSI, it was therefore necessary to allow for the variations in the operation timings. However, because of the increase in the size of the LSI, and the miniaturization of each element in the circuit, the variations continue to increase, so that it is becoming more and more difficult to develop an operable LSI unless the variations are restrained. Moreover, the temperature variations are difficult to estimate, and the extent of the temperature variation varies largely with time, so that the effects on the timings are not predictable.    (A2) At the time of the transition of the output signal, a through current flows from the power supply terminal to the ground terminal through a P-channel MOS transistor (hereinafter referred to as “PMOS”), and an N-channel MOS transistor (hereinafter referred to as “NMOS”) forming a CMOS, when they are ON (conductive) simultaneously. Such a through current causes waste of power. The through current leads to increase in the consumption current in the LSI as a whole. To cope with the temperature increase, an expensive package may have to be used, resulting in increase in the cost of the product. Moreover, the increased consumption current may be an obstacle in applications to portable equipment.    (A3) Parts of the LSI found to be affected by cross-talk after the layout design need to be modified by changing the wiring of the conductors, and/or changing the position of the driving circuits, to avoid cross-talk. However, such a modification may be difficult depending on the initial layout, and substantial revision of the circuit design or the layout design may be required.    (A4) The driving capacity of the driving section, such as CMOS inverters may not be sufficient for certain applications.